US3397583A - Control of vulcanization state and gradient in pneumatic tires - Google Patents

Control of vulcanization state and gradient in pneumatic tires Download PDF

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US3397583A
US3397583A US504727A US50472765A US3397583A US 3397583 A US3397583 A US 3397583A US 504727 A US504727 A US 504727A US 50472765 A US50472765 A US 50472765A US 3397583 A US3397583 A US 3397583A
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tire
tread
wear
cure
tires
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Lawrence R Sperberg
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Priority to DE19661573834 priority patent/DE1573834C3/de
Priority to LU52238D priority patent/LU52238A1/xx
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
    • B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
    • B29C35/0288—Controlling heating or curing of polymers during moulding, e.g. by measuring temperatures or properties of the polymer and regulating the process
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D30/00—Producing pneumatic or solid tyres or parts thereof
    • B29D30/06—Pneumatic tyres or parts thereof (e.g. produced by casting, moulding, compression moulding, injection moulding, centrifugal casting)
    • B29D30/0601—Vulcanising tyres; Vulcanising presses for tyres
    • B29D30/0633—After-treatment specially adapted for vulcanising tyres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C37/00—Component parts, details, accessories or auxiliary operations, not covered by group B29C33/00 or B29C35/00
    • B29C2037/90—Measuring, controlling or regulating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2021/00—Use of unspecified rubbers as moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/24—Condition, form or state of moulded material or of the material to be shaped crosslinked or vulcanised
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2030/00—Pneumatic or solid tyres or parts thereof

Definitions

  • FIG. 1 A first figure.
  • screened tires In order to increase the accuracy of the wear test, specially selected tires, which are measured and selected because of their low radial and lateral force variations, are included in the test in order to provide screened tires.
  • the screened tires have the percentage composition of the various compounds contained within the tread wearing surface varied to thereby provide a comparison between the wear resistance of the different tread compounds.
  • the optimum tread compound that is, the tread compound which exhibits the ability to outperform other tread compounds, may be readily selected and the process of vulcanization for manufacturing other tires may be adjusted in accordance with the test results to thereby provide a superior tire.
  • This invention relates to tire manufacture and tire testing; more particularly the invention is directed to a method that will permit the technical investigator to predict with extremely high precision the potential wear capabilities of various tire tread compositions, to determine accurately and precisely true differences in wear of tires of different manufacturers, and to increase the precision for measuring and determining the influence of individual construction changes and principles upon the fundamental property of abrasion resistance. Furthermore, it is possible to make such determinations and wear comparisons under vastly different conditions of wear severity and climatic conditions at greatly reduced expenditures of time and money that heretofore have been considered impossible or impracticable.
  • the invention further concerns a method of process control in which the state of cure of a rubber composition may be accurately derived and accordingly corrected to give an optimum cure gradient and state.
  • Vulcanization of rubber is a very complex phenomenon. During the process of vulcanization, cross-links occur between long macro-molecules that inhibit the movement of the molecule, thereby decreasing the plasticity while retaining the resilience of the rubber composition.
  • sulfur vulcanization for example, it is thought that the sulfur is combined both inter-molecularly as well as intramolecularly.
  • the normal in- 3,397,583 Patented Aug. 20, 1968 'ice terpretation being that an increase in cross-linkage is a measure of the increase in the state of cure. This is as it may be; but it is not held to be of significance by patentee so far as cure gradient or state of cure is concerned for the reason that cross-linkage, as presently derivable, cannot be directly and reliably related to true state of cure.
  • Reinforcement of rubber vulcanizates is of extreme interest and value since it contributes markedly to the ultimate life of most rubber products and specifically to pneumatic rubber tires. While reinforcement is an omnibus term, patentee regards it as the ability of a rubber composition to resist abrasive wear when applied to a pneumatic rubber tire. Reinforcement has been studied intensively since the first observation was made many years ago that carbon black contributed markedly toward improving the property of resisting abrasive wear. In todays technology, the class of carbon blacks known as HAF (high abrasive furnace) represents the most commonly used in tread compounds. HAF has replaced channel black as the principal material to impart abrasion resistance to a tread compound.
  • HAF high abrasive furnace
  • the other classes of carbon blacks that are used in tread compounds include ISAF (intermediate super abrasive furnace) and SAP (super abrasive furnace) type blacks.
  • the difierence in abrasive resistance between these carbon black types is moderate; if HAF is taken as channel would be 90-95%, ISAF, to and SAP, to
  • Reinforcement or resistance to abrasion, is also affected by the type of rubber compounded into the tread material.
  • Cold rubber brought about an improvement in abrasion resistance of 10-15 over hot GRS.
  • Polybutadiene rubber improves resistance 1% for each 1% of rubber hydrocarbon replaced by the polybutadiene rubber.
  • the improvement in abrasion resistance effected by choice and dosage of carbon black, choice and composition of the rubber types employed, etc., is relatively small as compared to the improvement that results in controlling the cure gradient in tires.
  • test procedures presently acceptable to industry cannot be used as accurate quantiatative tools for measuring cure gradient.
  • Indirect measurements or estimates of cross-linkage by the use of swelling tests and the like do not give a suitable indication of potential, absolute, or even relative changes in abrasion resistance.
  • the relative difference between the two systems is governed by the time and temperature of cure as well as the absolute dosage, for the type of cure employed has a marked bearing upon the uniformity of cure, or the cure gradient, as is evident in road wear tests Where the miles/ mil of rubber abraded away from the tread surface following a curve that is defined herein as the cure gradient.
  • the object of the present invention is to set forth a novel method of controlling the vulcanization of a tire so as to attain an optimum state of cure and the most desirable cure gradient in the tread composition.
  • Another object of the present invention is to set forth a novel method of obtaining and treating experimental data as related to tire tread wearing compounds.
  • a still further object of the present invention is to outline a novel test procedure for ascertaining the potential wear capabilities of various tire tread compositions under vastly different conditions of wear severity and climatic conditions and with great exactness and a low cost.
  • FIGURE 1 shows a plot of time and temperature versus cross-linking of the rubber molecules.
  • FIGURE 2 shows a plot of wear rate versus miles driven for several different types of cure gradient and state.
  • FIGURE 3 shows a plot of the relative amount of heat exposure by different sections of a tire while being vulcanized.
  • FIGURE 4 is a schematic representation of a crosssection of a tire showing three different levels or sections of the tread compound.
  • FIGURE 5 is a plot showing the relationship of the state of cure on the abrasion quality of a rubber composition.
  • FIGURE 1 shows the present concept of the state of cure as affected by time temperature of the vulcanization, which shows that cross-linking levels off with time of cure.
  • the present thought is that cross-linkage determinations do reflect the utimate state of cure conditions as they exist.
  • the present thought attributes such increase to the cures being tightened up, that is, an additional increment of vulcanization is postulated to have taken place due to the mechanical influence of wearing away of the tread.
  • FIGURE 5 wherein there are depicted curves illustrating patentees concept of the relationship between time of cure, fundamental state of cure, and resistance to abrasion.
  • the maximum resistance to abrasion is achieved at the minimum state of cure that will still yield a usable tire. This is represented by a point slightly to the right of point 3 of the upper curve and point 3 of the lower curve and by the horizontal line 6 or 6'.
  • Point 3 or 3' represents the minimum time of cure at which a usable tire may be obtained that will not fail due to insufiicient vulcanization.
  • 6 represents the maximum resistance to abrasion that can be expected from a rubber composition that was a higher state of cure; that, is the absolute dosage or cure condition is different from the upper curve and the entire curve represents a system of lower quality as compared to the upper curve.
  • Line 6 represents the maximum resistance to abrasion that can be expected from such a composition in comparison to line 6 which is an idealized situation that will yield the absolute in abrasion resistance. In examining these curves it is seen that there is a break in the curves at the optimum state of cure between numerals 2 and 3 (or 2'3).
  • FIGURE 4 there appears a sectional view of a tire having lines AA, BB, CC, drawn horizontally therethrough to represent various sections or levels through the thickness D-E of the tread wearing portion.
  • Tread portion AA will be the first tread portion to wear away with tread portions BB and CC following.
  • the curve of FIGURE 3 illustrates a cure rate for a tire that was vulcanized with heat being applied during the vulcanization process to both the inner and outer sides of the tire body in the tire mold.
  • a study of the heat transfer mechanism involved in the curing of the tread composition will show that a different total amount of energy or cure is received by each increment of tread depth as compared to another increment of tread at a different depth; that is, the total energy supplied by the tire mold to a section of the tire at the surface of the tread AA in FIGURE 4 will differ from the amount of energy received by the center portion or sub-surface of the tread BB of FIGURE 4.
  • the area under the curve AA of FIGURE 3 is indicative of the amount of cure that the tread compound at section AA of FIG- URE 4 receives, while the areas under the curves BB and CC are indicative of the amounts of cure received by tread portions BB and CC respectively of FIG- URE 4.
  • the areas under the individual curves are not directly comparable because the vulcanization rate of reaction from one compound to another is a function of the applied temperature.
  • the temperature coefficient of vulcanization is assumed to follow Arrhenius theory to give a coefficient of 1.4 to 2 as applied to chemical reaction rate changes where the reaction doubles in rate for each C. increase.
  • the point of minimum cure may vary between BB and C-C and depends upon the amount of heat energy applied from both external and internal sources as well as the actual time of cure.
  • the heat transfer gradient is more pronounced, and the point of minimum cure is more apt to occur at CC rather than AA or B-B, whereas in thinner passenger type tires the point may tend towards BB.
  • a thinner tire allows a closer approach to curves -B' or C of FIGURE 5 than is possible with the thicker truck tires; however, it is very difficult to approach curve C as the ultimate since even a slight excess of time or temperature can result in a marked influence in moving the cure curve from C to B or even to A.
  • the dotted extensions of the three curves AA, BB and CC of FIGURE 3 indicate residual cure, or that cure that takes place after the tire has been removed from the mold.
  • the temperature at the tread surface drops precipitously when the tire is removed from the mold but the innermost portions of the tire retain the impressed heats of vulcanization for relatively long time periods after removal of the tire from the mold.
  • This residual or after cure sometimes contributes well over 50% of the total cure in the undertread region of certain sizes and types of tires.
  • Many investigators fail to consider this residual or after cure that continues after the tire is rernoved from the mold and base their conclusions on cure time equivalents only on the heat exposure taking place up to the time that the mold is opened; hence substantial overcures in tires occur as a result of this defect.
  • tread portions AA and BB each receive some additional amount of overcure such as represented by numerals 2 and 2' of FIGURE 5.
  • This cure gradient, or progressive change in the state of cure through the tread depth is brought about by the inherent heat transfer mechanism of the tire vulcanization process.
  • a tire, as seen in FIG- URE 4, having such a cure gradient between AA and CC as described would exhibit excellent wear performance at tread depth CC with less perfect wear performance at tread depths BB and with still less perfect wear performance at AA.
  • the wear performanceof such a tire in actual road tests would follow a curve as represented by curve A (or A) in FIGURE 2.
  • Curve A" of FIGURE 2 represents an overcured tread composition where the minimum cure state corresponds to part BB of FIGURE 4 and physically lies someplace between the tread surface and the groove bottoms.
  • the initial increase in wear performance represents the beneficial ef fect of cure gradient followed by the deleterious effect of overcure as the wear performance test progressed.
  • the measured imperfections in a tire relate to imbalance, external radial runout, internal radial runout, loaded radial runout, radial force variation and lateral force variation.
  • Radial runout is simply the variation of a tire from a perfect planar circle, both interior and exterior, when said tire is mounted on a dimensionally perfect wheel.
  • Radial and lateral force variation represent measured force variations in the two identified planes as a tire rtates through its 360 cycle.
  • Ordinarily produced tires have varying degrees of imperfectness as exemplied by the items identified above. A minimum level of acceptability of minor degrees of imperfectness may specify 25 lbs. radial and 7 lbs. lateral force variation under certain specified conditions of inflation, applied load, speed, tire size, etc.
  • the varying levels of arbitrary acceptability may be determined from a performance graph derived from a sufficient sample size to characterize such graph accurately wherein the magnitude of a specific imperfection is plotted against cumulative precent of total sample.
  • the limits fall approximately at the 68% point of each individual curve of percent of total versus radial force variation and percent of total versus lateral force variation, which point represents a plus or minus one standard deviation of variation of the specific imperfection.
  • roughly one-third of commercially produced tires fall outside this specification and would be excluded from the test sample.
  • the point of exclusion whether by absolute value or by precent of total sample is determined by empirical means. With reference to the specification of 25 and 7 lbs.
  • lateral force variation is less than 3% and that the standard deviation varies 1% for each 10 lbs. radial force variation.
  • tires having varying degrees of imperfectness generally have a tire life related to the degree of imperfectness, and in this respect the general analogy may be drawn that tire durability and rate of wear compared to a structurally perfect tire are both adversely affected in direct proportion to the magnitude of the imperfection. Since a wear performance test aimed at determining the cure gradient and state would be adversely affected by tire failures it is obvious that tires having major variations from being structurally perfect should be excluded from the test by virtue of their potentially poor anticipated tire life as well as for their adverse undesirable effect upon tire wear.
  • a screened tire is identified as one that is carefully selected with these elements held to a minimum so as to approach a perfect tire from structural consideration.
  • the degree of screening employed will depend upon the precision required and the cost incurred.
  • a screened tire that is road tested on a vehicle in perfect mechanical condition and treated in such a manner so as to eliminate or minimize the common factors affecting absolute rate of wear results in a normal distribution curve of wear variation that is very narrow and peaked in comparison to a broader shallower curve when such screening selection is not employed. This permits decisions to be made at high confidence levels even when small differences in abrasion resistance are being considered.
  • Multi-tread section road testing tires are those tires that are comprised of more than a single tread wearing compound as the tread composition.
  • a two way tire would be comprised of one tread wearing composition for and a second tread wearing composition the remaining 180 about the tread surface of the tire.
  • Patentee has developed a technique in which test tires may be fabricated using as many as ten different brands of rubber vulcanized in segments or sections in the tire mold to produce a tread wearing compound each 36 of the tread surface, which 36 each represents a different stock or brand of rubber.
  • the purpose of multi-tread section tires for measurement of the wear properties is to obtain reproducible accuracy and precision of wear measurement at greatly lowered costs. Improved precision and accuracy flow from the elimination or minimization of the individual factors affecting the absolute rate of wear of whole tirese.g., axle end, driver severity, power supply, speed, load, inflation, rim size, texture of abrading surface, ambient air and road surface temperature, cross wind effect, and wet miles, to mention some of the more important factors that regulate and influence the absolute rate of tire wear not already regulated by the imperfectness of the tire itself.
  • any wear that is not a reflection of the true wear potential of the tire or tread compound being investigated is termed rnal wear or bad wear.
  • a screened tire, whether whole or multitread, that is tested under properly and rigidly controlled conditions so as to hold the variables to an absolute minimum will give reliable and reproducible results as to wear performance of whole or multitread compositions provided the wear results are properly interpreted in accordance with a recognition of the cure gradient and state that exist in the tread compound(s) and the degree of screening employed.
  • the standard deviation of a whole tire' wear test wherein one variable or treatment 'is compared to another, is governed by the principal relationship of the standard deviation divided by the square root of n.
  • the standard deviation is the standard deviation of wear variation existent for single tires while It is the number of tires involved in each test.
  • the standard deviation of wear variation of a single tire Wear test run for 10,000 miles on a slow wear route wherein no screening selection is employed is of the order of eight percent. It is unusual to test more than four tires of a treatment in any single controlled wear test for cost reasons; hence, the standard deviation of wear variation of four tires of treatment A versus four tires of treatment B would be eight divided by the square root of four or four percent.
  • a selected screened new whole tread tire, a screened multitread the built and cured in entirety in a normal factory operation, or a selected screened tire that has been det-readed, supplied with a new multi-tread vulcanized thereon under closely controlled curing conditions, and screened to ascertain its dynamic flexibility will respond to road wear tests in a manner to give reliable wear data of a highly reproducible order.
  • the road test wear data may in turn be used to obtain a clear picture of the state of cure and the profile of the cure gradient and cure state as existent between the different treatments being investigated. This cure gradient and cure state provide a tremendous tool in process control.
  • the cure gradient obtained from the statistically designed wear tests will show the process controller the type of correction required in his specific cure to obtain an optimum cure gradient.
  • the statistically designed Wear tests coupled with the specific mechanical procedures employed 7 for selecting and preparing screened tires with appropriate statistical designs interpreted through the recognition of the effect of the cure gradient and cure state enable one to determine the relative wear performance of any tread wearing composition of matter with respect to any other com-position of matter referred to as a control under any level of wear severity and under any climatic condition at a cost and expenditure of time equal to one-half to onetwentieth that of other known testing procedures, and at an experimental error lower than heretofore possible.
  • a statistically designed screening wear test may be conducted with any number of variables or treatments ranging from two to one hundred (although most wear experiments are concerned with from four to sixteen treatments) with any number of tires ranging from one to one hundred (although :most experiments will be built using from one to eight tires), and with from two to ten different tread rubber compounds peripherally placed in segments around the tire, with each tread segment having a multitude of different points of wear measurements taken on its individual surface.
  • the type of statistical design may vary from completely balanced block types to partially balanced incomplete block designs with two associate classes to partially balanced incomplete blocks with no associate classes.
  • the mathematical solutions to these different types of statistical designs may be made in accordance with established mathematical procedures as exemplified in a publication of Bose, Clatworthy, and Shrikhande (Reprint No.
  • Patentee prefers to use statistical designs where lambda(s) are always positive for ease of mathematical solution, but designs where one lambda might be zero can also be used.
  • the symbol, lambda simply refers to the number of times any treatment is directly compared to any other treatment.
  • the tire for its multi-tread wearing composition which contains the rubber compositions that are to be road tested.
  • the thickness and width of the tread stock being supplied is controlled to .020 inch maximum variation so as to ensure a reasonably low radial and lateral force variation lbs. and 7 lbs. respectively).
  • the tire is cured using internal as well as external heat in as little as fourteen minutes cure time for a 7.50-14 size tire where new tire type tread formations are being studied, using 250 p.s.i. internal pressure. All groove bottoms are deliberately made flat so as to improve the precision and accuracy of the tread depth measurements.
  • the screening tires are then post inflated and tread depth measured for each groove at approximately 1 inch intervals for the entire tire circumference.
  • Treatment appears herewith for the 4 tires that are made up as
  • the small sufiix numbers after the individual abrasion index values indicate the tire number from which the calculation was made. It is obvious that in an actual experiment wherein various errors can enter, that the pairs of experiments (or triples) will not yield identical values.
  • the average value of 103.0 in the lower right hand corner of the calculation represents the distortion of averaging reciprocal numbers and is inherent in any of the mathematical solutions employed if ordinary whole numbers are employed, but it may be eliminated completely if a logarithmic model is employed.
  • the average abrasion index is arbitrarily established as 100.0% for the system under discussion, the average value of logarithms would have been 2.0000 where the figure 103 appears.
  • the average abrasion wear values in the extreme right hand column that have been adjusted to the average wear performance base of 100.0% from the base of 103.0% would not be affected.
  • Example 1 The investigator wishes to determine the specific conditions of cure to employ for a specified tire so as to achieve the highest resistance to abrasion with-the most desirable cure gradient.
  • a sufficiently large number of tires to enable a satisfactory screening selection to be made are cured out using the standard conditions of time in mold, external mold temperature and internal applied heat and pressure. Since whole tires are involved an extremely rigid specification covering sample nonuniformity will be employed. Specifically only tires having less than 7 lbs. radial and 2 /2 lbs. lateral force variation for example will be selected for the controlled road wear test. Similarly tires employing a difference in the cure conditionsi.e., a shorter time or higher or lower applied external or internal temperature would then be prepared and selectively screened to the same selection specification.
  • the choice of the number of tires of each treatment to be road tested is regulated by the required confidence level for a minimum abrasion difference that will permit proper analysis.
  • the tires of all treatments involved is then road tested under rigidly controlled conditions so as to ensure minimization or neutralization of the individual and collective factors affecting road wear, and measured at suflicient intervals with suflicient accuracy so as to enable accurate and precise non skid versus milage curves to be constructed for each of the treatments.
  • Analysis of the cure gradient effect (and cure state) determines the proper cure conditions to be employed to achieve the maximum abrasion resistance, or if the initial selection of treatment variables were initially improper, such conclusions would be dictated by the analysis of the cure gradient and cure state effects so that new cure conditions could be employed in another experiment.
  • the road test is most conveniently conducted upon a fast wear course so as to enable the tires to be worn out in the minimum mileage although greater mileages to wear the tires out would not affect the conclusions.
  • Example 2 It is desired to determine the influence of a construction change in a tire upon abrasion and overall performance.
  • a rigid specification for tire selection is employed so as to permit a minimum number of tires to be road tested and still yield sufiiciently accurate wear data to permit decisions to be made at a high confidence level if only small differences in wear should be encountered. If the experimental treatments affected the fundamental time temperature cure curves as a consequence of the tire being thicker or thinner or having a higher thermal conductivity the influence of this phenomenon could be readily determined from the cure gradient effect upon abrasion resistance. As in the previous example, complete and accurate non skid loss versus mileage curves for each treatment is determined.
  • Example 3 the investigator wishes to determine the optimum factory mixing and extrusion conditions to employ for a given tread stock formulation so as to attain the maximum abrasion resistance in the finished tire.
  • the entire Work project is performed in a factory Where the green tire can be built and cured using the specific cure conditions that have been established. It may be desired to determine the precise effect of Banbury mixing time (e.g., 5 min. vs. 4 min), the optimum number of remills to employ, or the effect of repeated remilling upon the ultimate abrasion property.
  • Banbury mixing time e.g., 5 min. vs. 4 min
  • a suitable statistical design is selected and the tires built with multisection treads and then cured.
  • Example 4 The investigator in this instance might be an independent chemical manufacturer or supplier who does not have complete tire factory facilities available to him. He de sires to determine the proper amounts and preferable types of organic accelerators to employ for optimum resistance to abrasion.
  • Regular production tires of the size desired are first screened for their relative degree of imperfection and are then detreaded and fitted with individual tread sections in accordance with a previously selected statistical design.
  • the tires so built are then cured in a mold with special flat bottomed grooves to improve the precision of the depth measurement determination, using heat application both internally as well as externally so as to achieve essentially the same time temperature relationships at the tread surface and at the undertread as would characterize the factory operation he desires to duplicate.
  • the tires are post inflated after removal from the curing mold.
  • Example 5 In this example the investigator desires to determine the relative Wear performance of a new composition of tread matter with reference to a standard material with which he is familiar. He further desires to know how said performance might vary as a result of a change in terrain from severe mountain to flat plain, from northern cold climates to hot equatorial regions. Only a limited number of treatments are involved and these have been previously studied to finitely adjust curing rates so that all are equal. An appropriate statistical design is selected which will yield the desired degree of precision and accuracy.
  • the tires may be built in a factory operation as in Example 3 or using screened detreaded tires as described in Example 4. Two sets of tires would be prepared.
  • two sets of tires would comprise only four or at the most six tires.
  • One of the sets would be oven aged for one month at C. in a protected non oxidizing atmosphere to simulate the influence of heat aging that would be undergone by a tire in use in a hot climate during its useful life.
  • the unaged and aged tires may then be tested under rigidly controlled conditions of speed, load, etc., preferably over a fast wear route.
  • the individual tread sections is then measured finitely in a multiplicity of places at appropriate intervals so as to ensure being able to characterize the wear throughout the entire depth of the tread compound.
  • the absolute wear of the control compound is determined from the non skid loss versus mileage curve along with the loss of the experimental treatment at the same mileage.
  • the relative performance of the experimental treatment in comparison to the control reference material may be readily determined.
  • the influence of the heat aging use upon either materials both as to absolute and relative effects can accordingly be determined so as to enable the investigator to postulate how the experimental material could be expected to perform relative to the reference material under any of the specified conditions as outlined at the beginning of the present example.
  • a method of controlling the process of vulcanization for tire manufacturing comprising:
  • each individual component of said tread compound represents a variation in the preparation treatment and is placed in individual segments about the periphery of the tire to form a continuous multitread tire;
  • one of the tread segments includes a standard rubber compound having a known history and wherein the wear rate is determined by road testing the tire under extremely high severity conditions; and adjusting the wear results of the different treatments by comparison with the standard tread segment compound to give reliable wear performance for other desired conditions of severity.
  • a method of establishing the optimum vulcanization rate for a whole tire tread wear compound comprising:
  • a method of controlling the process of vulcanization comprising:
  • a method of determining the tread life expectancy of a multiplicity of vehicle tires comprising:
  • a method of determining the optimum amount of a tire tread compounding ingredient in a tire tread comprising:
  • a statistically designed screening wear test for controling vulcanization processes of tire tread wearing compounds comprising:
  • a method of determining a truer wear potential of a tire by selectively eliminating tires possessing un desirable dynamic flexibility characteristics comprising: selecting a certain size sample of each treatment being studied, testing each tire of the lot samples for their radial and lateral imperfections, eliminating those individual tires whose radial and lateral imperfections exceed the imperfection existent in tires that characterize the point 68.27% of an infinitely large sample of like tires, Wear testing the remaining screened tires in such a sample size as to ensure a given degree of precision and accuracy, said wear tests to be performed in suitably controlled and regulated conditions so as to minimize or eliminate those factors having marked influence upon absolute wear rate.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Thermal Sciences (AREA)
  • Tires In General (AREA)
  • Heating, Cooling, Or Curing Plastics Or The Like In General (AREA)
US504727A 1965-10-24 1965-10-24 Control of vulcanization state and gradient in pneumatic tires Expired - Lifetime US3397583A (en)

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Application Number Priority Date Filing Date Title
US504727A US3397583A (en) 1965-10-24 1965-10-24 Control of vulcanization state and gradient in pneumatic tires
FR81274A FR1521354A (fr) 1965-10-24 1966-10-24 Procédé de fabrication et de contrôle de pneumatique et pneumatique ainsi obtenu
DE19661573834 DE1573834C3 (de) 1965-10-24 1966-10-24 Prüfverfahren von Luftreifen und Luftreifen hierfür
LU52238D LU52238A1 (en)van) 1965-10-24 1966-10-24
US00114997A US3722270A (en) 1965-10-24 1971-02-12 Non-destructive method of determining tire life

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3531996A (en) * 1968-10-23 1970-10-06 Monsanto Co Cure simulator
US3675009A (en) * 1970-05-18 1972-07-04 Phillips Petroleum Co Carbon black blending in rubber
US3688587A (en) * 1971-03-24 1972-09-05 Frank J Jirik Grain divider apparatus
US3722270A (en) * 1965-10-24 1973-03-27 L Sperberg Non-destructive method of determining tire life
US3769843A (en) * 1970-05-20 1973-11-06 L Sperberg Statistical designed experiments
EP0733456A3 (en) * 1995-03-20 1996-10-09 PIRELLI COORDINAMENTO PNEUMATICI S.p.A. System for optimizing cure and assuring quality of reversion susceptible rubber articles
US20070152362A1 (en) * 2004-09-03 2007-07-05 Greenwell I D Method for curing a thick, non-uniform rubber article
US20080149240A1 (en) * 2006-12-20 2008-06-26 Luneau Michael J Method for curing non-uniform, rubber articles such as tires
US20110062631A1 (en) * 2008-05-22 2011-03-17 Michelin Recherche Et Technique S.A. Curing Pin Material Optimization
WO2018017039A1 (en) * 2016-07-18 2018-01-25 Compagnie Generale Des Etablissements Michelin Monitoring of the cure state of a tire through the use of microwaves

Citations (3)

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US1845583A (en) * 1927-07-20 1932-02-16 Rosiers John B Des Sectional tire and vehicle wheel therefor
US1961726A (en) * 1928-07-20 1934-06-05 Morgan & Wright Apparatus for testing tires
US3039297A (en) * 1957-03-26 1962-06-19 Bayer Ag Test for determining optimum vulcanization

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1845583A (en) * 1927-07-20 1932-02-16 Rosiers John B Des Sectional tire and vehicle wheel therefor
US1961726A (en) * 1928-07-20 1934-06-05 Morgan & Wright Apparatus for testing tires
US3039297A (en) * 1957-03-26 1962-06-19 Bayer Ag Test for determining optimum vulcanization

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3722270A (en) * 1965-10-24 1973-03-27 L Sperberg Non-destructive method of determining tire life
US3531996A (en) * 1968-10-23 1970-10-06 Monsanto Co Cure simulator
US3675009A (en) * 1970-05-18 1972-07-04 Phillips Petroleum Co Carbon black blending in rubber
US3769843A (en) * 1970-05-20 1973-11-06 L Sperberg Statistical designed experiments
US3688587A (en) * 1971-03-24 1972-09-05 Frank J Jirik Grain divider apparatus
EP0733456A3 (en) * 1995-03-20 1996-10-09 PIRELLI COORDINAMENTO PNEUMATICI S.p.A. System for optimizing cure and assuring quality of reversion susceptible rubber articles
US5680315A (en) * 1995-03-20 1997-10-21 Pirelli Coordinamento Pneumatici S.P.A. System for optimizing cure and assuring quality of reversion susceptible rubber articles
US5784283A (en) * 1995-03-20 1998-07-21 Pirelli Coordinamento Pneumatici S.P.A. System for optimizing cure assuring quality of reversion susceptible rubber articles
US20070152362A1 (en) * 2004-09-03 2007-07-05 Greenwell I D Method for curing a thick, non-uniform rubber article
US7744789B2 (en) 2004-09-03 2010-06-29 Michlein Recherche et Technique S.A. Method for curing a thick, non-uniform rubber article
US20080149240A1 (en) * 2006-12-20 2008-06-26 Luneau Michael J Method for curing non-uniform, rubber articles such as tires
US20110062631A1 (en) * 2008-05-22 2011-03-17 Michelin Recherche Et Technique S.A. Curing Pin Material Optimization
WO2018017039A1 (en) * 2016-07-18 2018-01-25 Compagnie Generale Des Etablissements Michelin Monitoring of the cure state of a tire through the use of microwaves
WO2018017516A1 (en) * 2016-07-18 2018-01-25 Compagnie Generale Des Etablissements Michelin Monitoring of cure state through the use of microwaves
CN109996669A (zh) * 2016-07-18 2019-07-09 米其林集团总公司 通过使用微波监视固化状态
US10556393B2 (en) 2016-07-18 2020-02-11 The Curators Of The University Of Missouri Monitoring of cure state through the use of microwaves

Also Published As

Publication number Publication date
LU52238A1 (en)van) 1966-12-28
DE1573834A1 (de) 1971-03-11
DE1573834B2 (de) 1975-09-25

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